苯直接一步氧化合成苯酚

Direct Hydroxylation of Benzene to Phenol

苯直接一步氧化合成苯酚是开辟苯酚合成路线具有挑战性的热点课题之一。近年来研究和开发了以N2O、H2O2和O23种不同氧化剂体系为核心和主流的苯氧化合成苯酚路线。本文详细综述了目前3种不同氧化体系的研究进展和趋势,分析了各种合成路线的特点和工业应用前景。以N2O为氧化剂合成苯酚路线,技术趋于成熟,但N2O来源受限而影响其经济性和推广应用;以H2O2为氧化剂合成苯酚路线,是环境友好过程,有开发潜力,但技术还很不成熟,而且也因H2O2价格昂贵带来了经济成本问题;以O2为氧化剂、氢气为还原剂体系合成苯酚路线,是环境清洁可持续发展制备路线,具有很好的开发潜力,此外无机膜催化合成苯酚路线也更具吸引力。

The one-step process for direct hydroxylation of benzene to phenol is an attractive and challenging subject. So far, many research efforts made for direct hydroxylation of benzene to phenol are mainly focused on three preparation routes by adopting N2O, H2O2 and O2 as oxidants respectively. In this paper, the progress in these routes of direct hydroxylation of benzene to phenol is reviewed in detail. The characteristics and prospects of their industrial applications are also discussed. The route for direct oxidation of benzene to phenol with N2O as oxidant is technologically practicable, however, the process economics is strongly dependent on a cheap supply of N2O as a by-product in the production of adipic acid. On-purpose production of N2O as a feedstock for the process is economically unfeasible now. Thus the application of the technology is severely limited to just a few sites where N2O from adipic acid manufacture can be readily accommodated in the downstream direct oxidation process. The route for phenol preparation with H2O2 as oxidant is an environmentally friendly process, however, it is technologically unfeasible now due to lower efficient utility for H2O2 and higher phenol production cost. And also expensive H2O2 shows negative effect on the economics of its industrial application. In comparison, the process for direct hydroxylation of benzene to phenol with O2-H2 system is an environmentally clean and sustainable route. It is of potential prospect in both academic research and technological development aspects. The route of direct oxidation of benzene to phenol with O2-H2 system by using inorganic membrane reactor is more attractive because of its higher conversion, selectivity and safer operation.